Simulating an Acoustic Cavity for Single Pixel Photoacoustic Imaging

Abstract

This research project presents a COMSOL model that simulates the measurement of elastic waves within a solid domain generated by the photoacoustic (PA) effect. The model may facilitate the development of a novel, forward-looking PA endoscope that integrates a relatively new PA imaging method for the first time. PA endoscopy is used to image tissue layers up to several millimeters deep, with applications including intravascular imaging and imaging of the gastrointestinal tract. The most challenging requirement is achieving a frame rate exceeding 20 Hz while maintaining a reasonable resolution. Recently, novel imaging techniques, such as photoacoustic topography through an ergodic relay (PATER), have been explored based on a single sensor and acoustic cavity, which reduces complexity and speeds up frame rates. A numerical model could be beneficial to facilitate the design of this novel PA endoscope. However, the modelling of this process is not straightforward due to the time dependency and high frequencies involved. An important aspect of this model is a highly tunable but representative PA signal source. The ability to change the input signal such that the frequency content does not exceed what could be measured allows for using a mesh size that is not smaller than necessary. Validation of a 2D version of the model against experimental data was performed, and the computational costs were explored with the help of the DelftBlue cluster.